The present invention relates to graphics displays and in particular to raster scan type displays that use a cathode ray tube (CRT). Specifically the present invention relates to a technique and apparatus for increasing the resolution of such graphics displays, thereby enabling the smoothing of the appearance of the figures that are generated. The improvement essentially comprising the addition of three planes to an image memory and the addition of an x-y decoder, driver and x-y auxiliary yoke to the CRT for positionally correcting the electron beam of the CRT within each pixel of any figure depending upon a peculiar position correction code that is generated for these pixels by the graphics generator of the display.
Previously when displaying graphics figures, upon close inspection of a display's screen, it would be apparent to an observer that the graphics figures were not produced with a smooth definition between the successive pixels that comprised each graphics figure. While the relative smoothness of each graphics figure was less noticeable to an observer as he positioned himself at greater distances from the display's screen, in many applications, it was necessary to remain close to the screen. Therefore it is desirable to generate smoother appearing graphics figures and thereby alleviate eyestrain and produce a more exact representation of each graphics figure.
While numerous algorithms and techniques are known in the art for determining the individual points that comprise any given graphics figure, each algorithm or technique generally suffers from some error that accumulates as a graphics figure is generated. The primary component of the error, however, generally results from the limited resolution of most commercially available CRT's, and which CRT's typically provide for a resolution of 512 by 512 pixels or a corresponding binary x, y resolution of nine bits by nine bits.
It is therefore a primary object of the present invention to provide a graphics display having an increased resolution.
It is another object of the present invention to increase a CRT's resolution via the generation of a position correction code for each pixel of a figure and the addition of an auxiliary yoke and associated decoder, drive circuitry to drive the auxiliary yoke's x and y coils in response thereto, and thereby correctively deflecting the electron beam, as necessary, for each pixel of a displayed figure.
These objects and others will become more apparent upon a reading of the hereinfater described method and apparatus.